What would you like me to elaborate on? If you check out the aquarium products website, you will see that the TMC110 has claimed usefulness up to 3,300 gallons. Now, I’d take that number with a degree of suspicion, but I see nowhere that it’s ‘rated’ for 200 gallons. Makes no sense actually. You will find that gallon ratings for all kinds of reef tank equipment are all over the place, so it does require a little sleuthing to try to equate one with another. With UV units, watts aren’t always directly comparable (depends a lot on the bulb) but all things equal, 110 is going to outperform 40. Maybe that’s what you mean by elaboration .